Optimization Method And Experimental Study Of Curved Thin Wall Parts By Micromilling

Miniature curved thin wall parts are widely used in precision medical instruments,micro electric spark electrodes,micro turbines and other fields.Because of its small size(the thickness always less than 100?m)and poor stiffness,it is difficult to machining it with high precision.In recent years,it has become a trend to use micromilling technology to manufacture micro thin wall parts with large aspect ratio.However,Micro milling is a kind of micro cutting technology,which is different from the traditional cutting.The cutting mechanism and law involved in it still need to be studied further to improve the machining accuracy and efficiency of micro thin wall features.Therefore,this paper studies the cutting parameters and process of micromilling of micro thin wall parts.In this paper,brass and copper are used as workpiece materials,and the influence of parameters and process on the dimensional error,burr and deformation of thin wall in the process of thin wall micromilling is studied by orthogonal and response surface method(RSM)and other experimental method.Firstly,orthogonal cutting experiments are carried out to obtain the influence law of various parameters(Spindle speed n,feed engagement f_z,axial depth of cut a_p and radial depth of cut a_e)on surface roughness,dimensional error and burr in the milling process of curved thin wall parts,identify the key parameter that has the greatest influence on each indexes,and obtain the optimal parameter combination when the three evaluation indexes are taken as the optimization target respectively.By using the comprehensive equilibrium analysis method,the appropriate parameter combination is obtained.Finally,the verification experiments of process optimization are carried out,the results show that the optimization results effectively inhibits the formation of burr,reduces the dimensional error,and fabricate the high quality thin wall parts.On the basis of the above research,the interaction influence law of each parameter and the optimization method to reduce the thin wall deformation,dimensional error and burr height are further explored.Firstly,the thin wall milling deformation mechanism was proposed to solve the problem of side wall excessive cutting in milling of curved thin wall.The simulation study of thin wall milling deformation of curved thin wall is carried out by using finite element technology,which revealed the complex deformation mechanism in laminated milling of thin wall parts with weak stiffness.The response surface method is used to analyze the interaction influence mechanism of each parameter on the milling force so as to control the milling force and reduce the deformation of the thin wall.By changing the parameters and process,optimizing the structure of the micro end mill and improving the holding accuracy of the tool handle,the milling deformation is suppressed effectively,and the experimental verification is carried out.Secondly,in view of the burr and dimensional error in the milling process of curved thin wall,the response surface method is used to analyze the interaction effect of each parameter and establish mathematical model,which effectively describes the mathematical relationship between each evaluation index and the key parameters.Furthermore,based on the mathematical model of burr height and dimensional error,the multi-objective particle swarm optimization(MOPSO)algorithm is used in multi-objective optimization.It has been proved that,the effect of multi-objective optimization is better than the orthogonal experiment optimization.Finally,the micromilling experiments of thin wall parts with different materials and a variety of weak-stiffness complex curved thin wall structures are carried out,and high-quality micro-turbine disks and other parts were fabricated,which verified the high quality milling method of complex curved thin wall in this paper.In this paper,the methods of parameter significance analysis,model establishment,process optimization and deformation control in the micromilling of micro curved thin wall are of certain reference significance for the high quality machining of other thin wall parts with weak stiffness and complex surfaces.